In the liquid crystal display element, a liquid crystal layer is sandwiched between a pair of substrates, and the liquid crystal layer contains a liquid crystal composition. Such liquid crystal display element is widely used in image display devices such as a liquid crystal television, a monitor for a computer, a mobile phone, an information terminal, and a game machine.
Representative examples of a display method of the liquid crystal display element include a twisted nematic (TN) type, a super twisted nematic (STN) type, an electrically controlled birefringence (ECB) type, and the like. Examples of an active matrix type liquid crystal display element using a thin-film transistor (TFT) include a VA type in which liquid crystal molecules are vertically aligned, and an in-plane switching (IPS) type in which liquid crystal molecules are horizontally aligned or a fringe field switching (FFS) type, which is a kind of the in-plane switching (IPS) type.
In these liquid crystal display elements, a nematic liquid crystal is used, and a liquid crystal composition whose dielectric anisotropy (Δε) is positive or negative is used according to the kind of the element.
Meanwhile, investigation has been conducted on optimizing the liquid crystal composition by simulating the characteristics of the liquid crystal composition in a desired display mode using an elastic constant peculiar to the liquid crystal composition. It has been expected that, by adopting such method, an n-type liquid crystal composition can be developed with high efficiency. The behavior of the liquid crystal molecules can be described as three modes: splay, twist, and bend, depending on the external electric field. As for the elastic constant, there are a splay elastic constant (hereinafter, may be referred to as “K11”), a twist elastic constant (hereinafter, may be referred to as “K22”), and a bend elastic constant (hereinafter, may be referred to as “K33”), corresponding to these modes.
As a method for optimizing the characteristics of the liquid crystal composition using K11, and K22, and K33, for example, a method of preventing disarray of the arrangement of liquid crystal molecules (disclination) in the center portion of a pixel electrode or between the pixel electrodes fey selecting a liquid crystal composition satisfying relational expressions of K33/K11≥1.5 and 1.7≤(K33/K22−K33/K11)≤2.7 and having an average transmittance of equal to or greater than 0.6 as the liquid crystal composition to be used in an IPS type or an FFS type liquid crystal display element, thereby enabling high definition display in a liquid crystal display element has been disclosed (refer to PTL 1). It is disclosed that, according to this method, the average light transmittance of the liquid crystal composition is improved by preventing disclination.
However, in PTL 1, there is no description regarding an n-type liquid crystal composition, and the method described in PTL 1 is not intended for an n-type liquid crystal composition. Furthermore, description was not made regarding improving light transmittance in PTL 1, and a method for measuring K11, K22, and K33 of the n-type liquid crystal composition is not disclosed in PTL 1 in the first place. Thus, validity of the measured values cannot be verified.